1. Field of the Invention
This invention relates to the field of electro-magnetic radiation concentrating systems. In particular, this invention pertains to the field of lenses. Still further, this invention relates to the field of refracting mirror type lenses. More in particular, this invention relates to the field of Fresnel type lenses modified to provide both refraction and reflection of incident radiation impinging on the lens.
2. Prior Art
Multi-lenticulated lenses are known in the art. Additionally, Fresnel type lenses for producing either a line focus or a point focus are also known in the prior art. However, Fresnel type lenses when utilizing linear lenticulations have been provided as reflecting surfaces. In such prior art lenses, the inclined surfaces facing the source of the incident radiation have been mirror coated to provide a direct reflection mode of the radiation to either a point focus or a line focus. In such prior art lenses, the reflected radiation has been interfered with by successive lenticulation walls thus reducing the amount of reflected energy which is either directed to the line or point focus. This has caused a low efficiency of the concentration effect of the useful incident radiation.
Additionally, in prior art Fresnel type reflecting lenses, the inclined surfaces facing the source of radiation provides a series of surfaces which are exposed to the ambient environment and has been found to be contaminated with various particulates. Where the inclined surfaces are mirror coated, extreme care must be taken when cleansing such surfaces. This cleansing of the surfaces is a difficult and time consuming operation which increases the overall operating cost of such lens configurations.